This invention relates to the use of a blackcurrant lipid in a dietetic or pharmaceutical composition to prevent the adhesion phenomena responsible for certain thrombo-embolic, inflammatory and cancerous diseases.
It is known that polyunsaturated fatty acids of the .omega.3 and .omega.6 series have very important structural and functional roles. Polyunsaturated fatty acids can be defined by the number of carbon atoms, the number of double bonds and the number indicating the position of the first double bond counting from the methyl group which determines their metabolic family designated .omega.. Thus, in this nomenclature, dihomogammalinolenic acid (DHLA) is C20:3.omega.6, eicosapentaenoic acid (EPA) is C20:5.omega.3 and arachidonic acid (AA) is C20:4.omega.6. The fatty acids linoleic acid (LA, C18:2.omega.6) and alphalinolenic acid (ALA, C18:3.omega.3) are the essential precursors of the other acids of the two families which are not synthesized by mammalians. No metabolism allows passage from one family to the other. The conversion of LA or ALA into the respective upper members of the two families is obtained by successive desaturation and elongation with relatively low yields.
The prostaglandins form a family of substances which show numerous biological effects. DHLA, AA and EPA are transformed under the effect of cyclo-oxygenase into prostaglandins of the 1(PG1), 2(PG2) and 3(PG3) series, respectively. The PGS of series 1, 2 and 3 respectively comprise 1, 2 and 3 double bonds in their basic structure of C.sub.20 fatty acids including a cyclopentene group. Among other properties, the PG1S (emanating from DHLA) are capable of inhibiting the aggregation of blood platelets. By contrast, the eicosanoides of series 2 (emanating from AA), for example PG2, thromboxanes, for example PxA2, promote platelet aggregation. The eicosanoides of series 3 (emanating from EPA) have a similar role to the eicosanoides of series 1.
It is assumed that the effectiveness of EPA and DHLA in the prevention of cardiovascular diseases of the thrombo-embolic type is based on the favourable effects of the PG3S and PG1S compared with the effects of the PG2S.
In addition, the enzyme system lipoxygenase leads to hydroxylated fatty acids and to leucotrienes from the precursors AA and EPA. Recent studies suggest, in particular, that the compounds 13-hydroxyoctadecatrienoic acid (13-HODE), produced by the endothelial cells of the blood vessels, and 12-hydroxyeicosatetraenoic acid (12-HETE), produced by the platelets via the lipoxygenase, play an important part in the mediation of inter-cell adhesion and hence, in the pathogenesis of thromboses, inflammatory diseases and the dissemination of cancerous metastases. In simple terms, adhesion would be influenced by the regulators 12-HETE and 13-HODE positively by AA, the precursor of 12-HETE, and negatively by LA, leading to 13-HODE. In addition, DHLA is not susceptible to the lipoxygenase.
It has been proposed, for example in published French patent application no. 2 553 662, to add to a pharmaceutical composition or to a food product a mixture of a first fatty acid selected from EPA or docosahexaenoic acid (DHA) on the one hand and a second fatty acid selected from DHLA, cis-linoleic acid, gammalinolenic acid (GLA) on the other hand with the object of preventing cardiovascular diseases. In this patent application, the fatty acids in question must have been separately isolated from natural fats by iodination followed by saponification, solvent extraction of the fatty acids, methylation thereof, separation of the methylesters by chromatography and, finally, deiodination. EPA, for example, is obtained in this way from cod liver oil. The production of such a composition is particularly complicated.
In addition, EPA is particularly unstable. Finally, there are some people who cannot bear any recollection of bad tastes coming from fish oil, even in deodorized or encapsulated form.